This invention relates to an improved apparatus and method for reducing the electrical and heat loads on a building cooling plant.
Air conditioning plants that are used to cool buildings and other structures by either central plants for individual buildings or for district cooling application, frequently used chilled liquids such as water or brine solutions to transfer cooling capacity from the central refrigeration plant to the remote chilling coils and air handlers that are located in or near the space to be cooled. The normal cooling plant usually consists of absorption chillers, steam jet evaporation refrigeration, or electrically driven compressor chillers or other drive combinations that produce chilled liquid, usually at a temperature range of 35 degrees fahrenheit to 45 degrees fahrenheit. This chilled liquid is then pumped through interconnecting pipes to each remote chill coil in the air handling unit serving the space to be cooled. The associated air handler blower, driven by a motor, gathers heat and moisture laden air from the space to be cooled and directs the air, which typically is about 75 degrees fahrenheit, through the chilled water heat exchanger, which is normally 35 degrees to 45 degrees fahrenheit. As a result, heat from the warmer 75 degree fahrenheit air from the air stream of the building is transferred to the cooler fluid at 35 degrees to 45 degrees fahrenheit in the chill liquid coil. Heat, therefore, is removed from the space in the liquid and directed by interconnecting pipes back to the central chilling plant at about 55 degress fahrenheit. Here the heat is removed from the chilled liquid by a known refrigeration process and once again chilled liquid, at about 35 degrees to 45 degrees fahrenheit, is recirculated to the air handler for continuous cooling as required.
In the normal system, air that has some heat removed by the chill water coil is directed to the building supply distribution ducts at about 55 degress fahrenheit to absorb more heat from the structure. Heat accumulates in structures as a result of solar gain or because of heat generated within the structure itself. For instance, individuals, by the physical process of converting food to energy, create body heat at 98.6 degrees fahrenheit, which is given up to the cooler building temperature of 75 degrees fahrenheit at an average rate of about 600 BTU/h per person. Additionally, heat is generated by the machinery within the building as well. In a structure which requires 1,000 ton/hours of cooling, the air handlers and chill coils recover or collect 12,000,000 BTU's each hour that the system is fully loaded. This is the heat equivalent of two barrels of oil at 6,000,000 BTU's each, every hour. In a district cooling plant for each 1,000 ton/hour of continuous load, this is the equivalent of 17,520 barrels of heating oil each year.
A drawback to the cooling systems for structures known in the art is that the waste heat of a building, solar gain, body heat and equipment heat, are continuously adding to the cooling load of a normal cooling plant. Thus, there is a need in the art for providing a cooling plant load reduction device which directly utilizes this waste heat. It, therefore, is an object of this invention to provide a cooling plant load reduction apparatus and method, for efficiently utilizing waste heat within a building to reduce the electrical and heat load on the normal cooling plant.